On Fri, 2013-01-04 at 00:29 -0800, Anton Vorontsov wrote: > This commit implements David Rientjes' idea of mempressure cgroup. > > The main characteristics are the same to what I've tried to add to vmevent > API; internally, it uses Mel Gorman's idea of scanned/reclaimed ratio for > pressure index calculation. But we don't expose the index to the userland. > Instead, there are three levels of the pressure: > > o low (just reclaiming, e.g. caches are draining); > o medium (allocation cost becomes high, e.g. swapping); > o oom (about to oom very soon). > > The rationale behind exposing levels and not the raw pressure index > described here: http://lkml.org/lkml/2012/11/16/675 > > For a task it is possible to be in both cpusets, memcg and mempressure > cgroups, so by rearranging the tasks it is possible to watch a specific > pressure (i.e. caused by cpuset and/or memcg). > > Note that while this adds the cgroups support, the code is well separated > and eventually we might add a lightweight, non-cgroups API, i.e. vmevent. > But this is another story. > > Signed-off-by: Anton Vorontsov <anton.vorontsov@xxxxxxxxxx> > --- > Documentation/cgroups/mempressure.txt | 50 ++++++ > include/linux/cgroup_subsys.h | 6 + > include/linux/vmstat.h | 11 ++ > init/Kconfig | 12 ++ > mm/Makefile | 1 + > mm/mempressure.c | 330 ++++++++++++++++++++++++++++++++++ > mm/vmscan.c | 4 + > 7 files changed, 414 insertions(+) > create mode 100644 Documentation/cgroups/mempressure.txt > create mode 100644 mm/mempressure.c > > diff --git a/Documentation/cgroups/mempressure.txt b/Documentation/cgroups/mempressure.txt > new file mode 100644 > index 0000000..dbc0aca > --- /dev/null > +++ b/Documentation/cgroups/mempressure.txt > @@ -0,0 +1,50 @@ > + Memory pressure cgroup > +~~~~~~~~~~~~~~~~~~~~~~~~~~ > + Before using the mempressure cgroup, make sure you have it mounted: > + > + # cd /sys/fs/cgroup/ > + # mkdir mempressure > + # mount -t cgroup cgroup ./mempressure -o mempressure > + > + It is possible to combine cgroups, for example you can mount memory > + (memcg) and mempressure cgroups together: > + > + # mount -t cgroup cgroup ./mempressure -o memory,mempressure > + > + That way the reported pressure will honour memory cgroup limits. The > + same goes for cpusets. > + > + After the hierarchy is mounted, you can use the following API: > + > + /sys/fs/cgroup/.../mempressure.level > +~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ > + To maintain the interactivity/memory allocation cost, one can use the > + pressure level notifications, and the levels are defined like this: > + > + The "low" level means that the system is reclaiming memory for new > + allocations. Monitoring reclaiming activity might be useful for > + maintaining overall system's cache level. Upon notification, the program > + (typically "Activity Manager") might analyze vmstat and act in advance > + (i.e. prematurely shutdown unimportant services). > + > + The "medium" level means that the system is experiencing medium memory > + pressure, there is some mild swapping activity. Upon this event > + applications may decide to free any resources that can be easily > + reconstructed or re-read from a disk. > + > + The "oom" level means that the system is actively thrashing, it is about > + to out of memory (OOM) or even the in-kernel OOM killer is on its way to > + trigger. Applications should do whatever they can to help the system. > + > + Event control: > + Is used to setup an eventfd with a level threshold. The argument to > + the event control specifies the level threshold. > + Read: > + Reads mempory presure levels: low, medium or oom. > + Write: > + Not implemented. > + Test: > + To set up a notification: > + > + # cgroup_event_listener ./mempressure.level low > + ("low", "medium", "oom" are permitted.) > diff --git a/include/linux/cgroup_subsys.h b/include/linux/cgroup_subsys.h > index f204a7a..b9802e2 100644 > --- a/include/linux/cgroup_subsys.h > +++ b/include/linux/cgroup_subsys.h > @@ -37,6 +37,12 @@ SUBSYS(mem_cgroup) > > /* */ > > +#if IS_SUBSYS_ENABLED(CONFIG_CGROUP_MEMPRESSURE) > +SUBSYS(mpc_cgroup) > +#endif > + > +/* */ > + > #if IS_SUBSYS_ENABLED(CONFIG_CGROUP_DEVICE) > SUBSYS(devices) > #endif > diff --git a/include/linux/vmstat.h b/include/linux/vmstat.h > index a13291f..c1a66c7 100644 > --- a/include/linux/vmstat.h > +++ b/include/linux/vmstat.h > @@ -10,6 +10,17 @@ > > extern int sysctl_stat_interval; > > +struct mem_cgroup; > +#ifdef CONFIG_CGROUP_MEMPRESSURE > +extern void vmpressure(struct mem_cgroup *memcg, > + ulong scanned, ulong reclaimed); > +extern void vmpressure_prio(struct mem_cgroup *memcg, int prio); > +#else > +static inline void vmpressure(struct mem_cgroup *memcg, > + ulong scanned, ulong reclaimed) {} > +static inline void vmpressure_prio(struct mem_cgroup *memcg, int prio) {} > +#endif > + > #ifdef CONFIG_VM_EVENT_COUNTERS > /* > * Light weight per cpu counter implementation. > diff --git a/init/Kconfig b/init/Kconfig > index 7d30240..d526249 100644 > --- a/init/Kconfig > +++ b/init/Kconfig > @@ -891,6 +891,18 @@ config MEMCG_KMEM > the kmem extension can use it to guarantee that no group of processes > will ever exhaust kernel resources alone. > > +config CGROUP_MEMPRESSURE > + bool "Memory pressure monitor for Control Groups" > + help > + The memory pressure monitor cgroup provides a facility for > + userland programs so that they could easily assist the kernel > + with the memory management. So far the API provides simple, > + levels-based memory pressure notifications. > + > + For more information see Documentation/cgroups/mempressure.txt > + > + If unsure, say N. > + > config CGROUP_HUGETLB > bool "HugeTLB Resource Controller for Control Groups" > depends on RESOURCE_COUNTERS && HUGETLB_PAGE && EXPERIMENTAL > diff --git a/mm/Makefile b/mm/Makefile > index 3a46287..e69bbda 100644 > --- a/mm/Makefile > +++ b/mm/Makefile > @@ -51,6 +51,7 @@ obj-$(CONFIG_MIGRATION) += migrate.o > obj-$(CONFIG_QUICKLIST) += quicklist.o > obj-$(CONFIG_TRANSPARENT_HUGEPAGE) += huge_memory.o > obj-$(CONFIG_MEMCG) += memcontrol.o page_cgroup.o > +obj-$(CONFIG_CGROUP_MEMPRESSURE) += mempressure.o > obj-$(CONFIG_CGROUP_HUGETLB) += hugetlb_cgroup.o > obj-$(CONFIG_MEMORY_FAILURE) += memory-failure.o > obj-$(CONFIG_HWPOISON_INJECT) += hwpoison-inject.o > diff --git a/mm/mempressure.c b/mm/mempressure.c > new file mode 100644 > index 0000000..ea312bb > --- /dev/null > +++ b/mm/mempressure.c > @@ -0,0 +1,330 @@ > +/* > + * Linux VM pressure > + * > + * Copyright 2012 Linaro Ltd. > + * Anton Vorontsov <anton.vorontsov@xxxxxxxxxx> > + * > + * Based on ideas from Andrew Morton, David Rientjes, KOSAKI Motohiro, > + * Leonid Moiseichuk, Mel Gorman, Minchan Kim and Pekka Enberg. > + * > + * This program is free software; you can redistribute it and/or modify it > + * under the terms of the GNU General Public License version 2 as published > + * by the Free Software Foundation. > + */ > + > +#include <linux/cgroup.h> > +#include <linux/fs.h> > +#include <linux/sched.h> > +#include <linux/mm.h> > +#include <linux/vmstat.h> > +#include <linux/eventfd.h> > +#include <linux/swap.h> > +#include <linux/printk.h> > + > +static void mpc_vmpressure(struct mem_cgroup *memcg, ulong s, ulong r); > + > +/* > + * Generic VM Pressure routines (no cgroups or any other API details) > + */ > + > +/* > + * The window size is the number of scanned pages before we try to analyze > + * the scanned/reclaimed ratio (or difference). > + * > + * It is used as a rate-limit tunable for the "low" level notification, > + * and for averaging medium/oom levels. Using small window sizes can cause > + * lot of false positives, but too big window size will delay the > + * notifications. > + */ > +static const uint vmpressure_win = SWAP_CLUSTER_MAX * 16; > +static const uint vmpressure_level_med = 60; > +static const uint vmpressure_level_oom = 99; > +static const uint vmpressure_level_oom_prio = 4; > + > +enum vmpressure_levels { > + VMPRESSURE_LOW = 0, > + VMPRESSURE_MEDIUM, > + VMPRESSURE_OOM, > + VMPRESSURE_NUM_LEVELS, > +}; > + > +static const char *vmpressure_str_levels[] = { > + [VMPRESSURE_LOW] = "low", > + [VMPRESSURE_MEDIUM] = "medium", > + [VMPRESSURE_OOM] = "oom", > +}; > + > +static enum vmpressure_levels vmpressure_level(uint pressure) > +{ > + if (pressure >= vmpressure_level_oom) > + return VMPRESSURE_OOM; > + else if (pressure >= vmpressure_level_med) > + return VMPRESSURE_MEDIUM; > + return VMPRESSURE_LOW; > +} > + > +static ulong vmpressure_calc_level(uint win, uint s, uint r) > +{ > + ulong p; > + > + if (!s) > + return 0; > + > + /* > + * We calculate the ratio (in percents) of how many pages were > + * scanned vs. reclaimed in a given time frame (window). Note that > + * time is in VM reclaimer's "ticks", i.e. number of pages > + * scanned. This makes it possible to set desired reaction time > + * and serves as a ratelimit. > + */ > + p = win - (r * win / s); > + p = p * 100 / win; > + > + pr_debug("%s: %3lu (s: %6u r: %6u)\n", __func__, p, s, r); > + > + return vmpressure_level(p); > +} > + > +void vmpressure(struct mem_cgroup *memcg, ulong scanned, ulong reclaimed) > +{ > + if (!scanned) > + return; > + mpc_vmpressure(memcg, scanned, reclaimed); > +} > + > +void vmpressure_prio(struct mem_cgroup *memcg, int prio) > +{ > + if (prio > vmpressure_level_oom_prio) > + return; > + > + /* OK, the prio is below the threshold, send the pre-OOM event. */ > + vmpressure(memcg, vmpressure_win, 0); > +} > + > +/* > + * Memory pressure cgroup code > + */ > + > +struct mpc_event { > + struct eventfd_ctx *efd; > + enum vmpressure_levels level; > + struct list_head node; > +}; > + > +struct mpc_state { > + struct cgroup_subsys_state css; > + > + uint scanned; > + uint reclaimed; > + struct mutex sr_lock; > + > + struct list_head events; > + struct mutex events_lock; > + > + struct work_struct work; > +}; > + > +static struct mpc_state *wk2mpc(struct work_struct *wk) > +{ > + return container_of(wk, struct mpc_state, work); > +} > + > +static struct mpc_state *css2mpc(struct cgroup_subsys_state *css) > +{ > + return container_of(css, struct mpc_state, css); > +} > + > +static struct mpc_state *tsk2mpc(struct task_struct *tsk) > +{ > + return css2mpc(task_subsys_state(tsk, mpc_cgroup_subsys_id)); > +} > + > +static struct mpc_state *cg2mpc(struct cgroup *cg) > +{ > + return css2mpc(cgroup_subsys_state(cg, mpc_cgroup_subsys_id)); > +} > + > +static void mpc_event(struct mpc_state *mpc, ulong s, ulong r) > +{ > + struct mpc_event *ev; > + int level = vmpressure_calc_level(vmpressure_win, s, r); > + > + mutex_lock(&mpc->events_lock); > + > + list_for_each_entry(ev, &mpc->events, node) { > + if (level >= ev->level) > + eventfd_signal(ev->efd, 1); > + } > + > + mutex_unlock(&mpc->events_lock); > +} > + > +static void mpc_vmpressure_wk_fn(struct work_struct *wk) > +{ > + struct mpc_state *mpc = wk2mpc(wk); > + ulong s; > + ulong r; > + > + mutex_lock(&mpc->sr_lock); > + s = mpc->scanned; > + r = mpc->reclaimed; > + mpc->scanned = 0; > + mpc->reclaimed = 0; > + mutex_unlock(&mpc->sr_lock); > + > + mpc_event(mpc, s, r); > +} > + > +static void __mpc_vmpressure(struct mpc_state *mpc, ulong s, ulong r) > +{ > + mutex_lock(&mpc->sr_lock); > + mpc->scanned += s; > + mpc->reclaimed += r; > + mutex_unlock(&mpc->sr_lock); > + > + if (s < vmpressure_win || work_pending(&mpc->work)) > + return; > + > + schedule_work(&mpc->work); > +} > + > +static void mpc_vmpressure(struct mem_cgroup *memcg, ulong s, ulong r) > +{ > + /* > + * There are two options for implementing cgroup pressure > + * notifications: > + * > + * - Store pressure counter atomically in the task struct. Upon > + * hitting 'window' wake up a workqueue that will walk every > + * task and sum per-thread pressure into cgroup pressure (to > + * which the task belongs). The cons are obvious: bloats task > + * struct, have to walk all processes and makes pressue less > + * accurate (the window becomes per-thread); > + * > + * - Store pressure counters in per-cgroup state. This is easy and > + * straightforward, and that's how we do things here. But this > + * requires us to not put the vmpressure hooks into hotpath, > + * since we have to grab some locks. > + */ > + > +#ifdef CONFIG_MEMCG > + if (memcg) { > + struct cgroup_subsys_state *css = mem_cgroup_css(memcg); > + struct cgroup *cg = css->cgroup; > + struct mpc_state *mpc = cg2mpc(cg); > + > + if (mpc) > + __mpc_vmpressure(mpc, s, r); > + return; > + } > +#endif > + task_lock(current); > + __mpc_vmpressure(tsk2mpc(current), s, r); > + task_unlock(current); > +} > + > +static struct cgroup_subsys_state *mpc_css_alloc(struct cgroup *cg) > +{ > + struct mpc_state *mpc; > + > + mpc = kzalloc(sizeof(*mpc), GFP_KERNEL); > + if (!mpc) > + return ERR_PTR(-ENOMEM); > + > + mutex_init(&mpc->sr_lock); > + mutex_init(&mpc->events_lock); > + INIT_LIST_HEAD(&mpc->events); > + INIT_WORK(&mpc->work, mpc_vmpressure_wk_fn); > + > + return &mpc->css; > +} > + > +static void mpc_css_free(struct cgroup *cg) > +{ > + struct mpc_state *mpc = cg2mpc(cg); > + > + kfree(mpc); > +} > + > +static ssize_t mpc_read_level(struct cgroup *cg, struct cftype *cft, > + struct file *file, char __user *buf, > + size_t sz, loff_t *ppos) > +{ > + struct mpc_state *mpc = cg2mpc(cg); > + uint level; > + const char *str; > + > + mutex_lock(&mpc->sr_lock); > + > + level = vmpressure_calc_level(vmpressure_win, > + mpc->scanned, mpc->reclaimed); > + > + mutex_unlock(&mpc->sr_lock); > + > + str = vmpressure_str_levels[level]; > + return simple_read_from_buffer(buf, sz, ppos, str, strlen(str)); > +} > + > +static int mpc_register_level(struct cgroup *cg, struct cftype *cft, > + struct eventfd_ctx *eventfd, const char *args) > +{ > + struct mpc_state *mpc = cg2mpc(cg); > + struct mpc_event *ev; > + int lvl; > + > + for (lvl = 0; lvl < VMPRESSURE_NUM_LEVELS; lvl++) { > + if (!strcmp(vmpressure_str_levels[lvl], args)) > + break; > + } > + > + if (lvl >= VMPRESSURE_NUM_LEVELS) > + return -EINVAL; > + > + ev = kzalloc(sizeof(*ev), GFP_KERNEL); > + if (!ev) > + return -ENOMEM; > + > + ev->efd = eventfd; > + ev->level = lvl; > + > + mutex_lock(&mpc->events_lock); > + list_add(&ev->node, &mpc->events); > + mutex_unlock(&mpc->events_lock); > + > + return 0; > +} > + > +static void mpc_unregister_level(struct cgroup *cg, struct cftype *cft, > + struct eventfd_ctx *eventfd) > +{ > + struct mpc_state *mpc = cg2mpc(cg); > + struct mpc_event *ev; > + > + mutex_lock(&mpc->events_lock); > + list_for_each_entry(ev, &mpc->events, node) { > + if (ev->efd != eventfd) > + continue; > + list_del(&ev->node); > + kfree(ev); > + break; > + } > + mutex_unlock(&mpc->events_lock); > +} > + > +static struct cftype mpc_files[] = { > + { > + .name = "level", > + .read = mpc_read_level, > + .register_event = mpc_register_level, > + .unregister_event = mpc_unregister_level, > + }, > + {}, > +}; > + > +struct cgroup_subsys mpc_cgroup_subsys = { > + .name = "mempressure", > + .subsys_id = mpc_cgroup_subsys_id, > + .css_alloc = mpc_css_alloc, > + .css_free = mpc_css_free, > + .base_cftypes = mpc_files, > +}; > diff --git a/mm/vmscan.c b/mm/vmscan.c > index 16b42af..fed0e04 100644 > --- a/mm/vmscan.c > +++ b/mm/vmscan.c > @@ -1900,6 +1900,9 @@ restart: > shrink_active_list(SWAP_CLUSTER_MAX, lruvec, > sc, LRU_ACTIVE_ANON); > > + vmpressure(sc->target_mem_cgroup, > + sc->nr_scanned - nr_scanned, nr_reclaimed); > + > /* reclaim/compaction might need reclaim to continue */ > if (should_continue_reclaim(lruvec, nr_reclaimed, > sc->nr_scanned - nr_scanned, sc)) > @@ -2122,6 +2125,7 @@ static unsigned long do_try_to_free_pages(struct zonelist *zonelist, > count_vm_event(ALLOCSTALL); > > do { > + vmpressure_prio(sc->target_mem_cgroup, sc->priority); Why need function vmpressure_prio? It seems that it's reduncated. > sc->nr_scanned = 0; > aborted_reclaim = shrink_zones(zonelist, sc); > -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>